Study: Dogs accurately sniff cancer

A dog trained to sniff out colorectal cancer was almost as accurate as a colonoscopy in a study that suggests less-invasive tests for the disease may be developed.

The Labrador retriever was at least 95 percent as accurate as colonoscopy when smelling breath samples and 98 percent correct with stool samples, according to the study, published Tuesday in the medical journal Gut.

The dog's sense of smell was especially effective in early-stage cancer and could discern polyps from malignancies, which colonoscopy can't.

The results point to the existence of volatile organic compounds that might be the basis for non-invasive, early colorectal-cancer diagnostics, wrote the researchers led by Hideto Sonoda of Kyushu University in Japan.

"Most striking is the ability of the dogs to detect bowel cancer at its earliest stages," Trevor Lockett, a bowel-cancer researcher with the Commonwealth Scientific and Industrial Research Organisation in Australia, said in an e-mail.

Most current non-invasive tests for bowel cancer identify later-stage disease far more efficiently than early stage, Lockett said.

"Detection of early stage cancers is the real holy grail in bowel cancer diagnosis because surgery can cure up to 90 percent of patients who present with early stage disease," he said.

"This study shows that a specific cancer smell does indeed exist," the researchers said in the study. "These odor materials may become effective tools in screening."

There were about 102,900 new cases of colon cancer and 39,760 cases of rectal cancer in the United States last year, according to the American Cancer Society. The society said 51,370 patients died from the disease.